MYD88 L265P mutation is present in 29% of ABC patients and is associated with extranodal disease (breast, testis, stomach, central nervous system) and poor outcome.5 In contrast, the GCB subtype is characterized by frequent mutations in phosphoinositide 3-kinase (PI3K) and apoptotic pathways. The gene discussed is MYD88; the disease is aneurysmal bone cyst.